Cooling rate effects on the magnetization of volcanic rocks: Some implications for paleointensity determination
Effects of variation of cooling rate in the acquisition of thermoremanent magnetization (TRM) are analyzed on a suite ofvolcanic rocks. We use a three-step cooling rate experimental procedure applied at three distinct temperatures of TRM acquisition.Sixteen selected, thermally stable samples from La...
| Autores: | , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2006 |
| País: | México |
| Institución: | Universidad Nacional Autónoma de México |
| Repositorio: | Redalyc-UNAM |
| OAI Identifier: | oai:redalyc.org:56845205 |
| Acceso en línea: | https://www.redalyc.org/articulo.oa?id=56845205 |
| Access Level: | acceso abierto |
| Palabra clave: | Ciencias de la Tierra Cooling rate paleointensity volcanic rocks rock magnetism |
| Sumario: | Effects of variation of cooling rate in the acquisition of thermoremanent magnetization (TRM) are analyzed on a suite ofvolcanic rocks. We use a three-step cooling rate experimental procedure applied at three distinct temperatures of TRM acquisition.Sixteen selected, thermally stable samples from Late Quaternary lava flows were given a pTRM (300°C) at a slow cooling rate.The acquired intensities were measured at room temperature. A second pTRM was applied to the same specimens using a fastcooling rate, and the acquired intensities were measured at room temperature. Finally a third pTRM was induced as in the firststep, using a slow cooling rate. The procedure was repeated to create pTRMs at higher temperatures of 450° and 550°C.Corresponding percent variations between magnetization intensities acquired at slow-fast and at slow-slow cooling rates werecalculated to investigate the influence of cooling rate on TRM intensity acquisition, and on TRM acquisition capacity. Weobserve values as high as 300 % in the former case (300 °C). Intensity of the ancient geomagnetic field obtained from volcanicrocks could be overestimated by at least 15% due to a variation in cooling rate normally employed in the laboratory, as comparedto slower rates found in nature. |
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